Coating composition comprising a vinyl halide resin and a hydroxy polycarboxylic acid



. ins have been on the market household,

the metals themselves and the Patented Apr. 13, 1 948 ooarmo ooMrosmoN vnwr. mum: nnsm POLYCARBOXYLIG A can L. Shaphjo; Grafton, r

Lynnwood J., a corporation of New assignments, to Newark, N.

No Drawing.

CID

oommsmo A AND a: mznnoxx assignor, by memo Laboratories, Inc..

J s y Application July 31; 1942, Serial No. 453,056

13 Claims. (Cl. 260-41) Thisapplication is a continuation-impart of my applications Serial Numbers;327,'l38, filed April 3, 1940, and 331,112, flled'April 23, 1940, both now abandoned. I

The present invention relates to compositions containing vinyl halide resins. Vinyl halide resfor a number of years and have been applied for various purposes in industry. Coating compositions based on these resins have found considerable application because of a number of very desirable properties. Since the resins are .tasteless they have been used for lining containers intended for substances such as foods, Juices and beverages. resins are quite resistant to alcohol and numerous other solvents they have often found application for finishing various types of furnituresuch as hotel and hospital furniture. Vinyl resin-containing coatings furthermore are resistant to the actions of alkalies, acids and most of the corrosive chemicals found in industry.

They also resist moisture, grease, humidity, etc, and are hard andabrasion resistant and with standweathering conditions in a superior mane ner.

However, vinyl halide resincompositions have heretofore been limited in use because of the incompatibility of vinyl halide resins with certain materials and metals. It has not been possible to apply them directly tosurfaces containing zinc, tin or iron for they tend to become darkened or black when applied directly to these bake vinyl halide surfaces. It is customary to Since the resins in order to cause them to become resistant to corrosion and usually higher temperatures or longer times of baking create more resistance. The objectionable blackening is considerably accelerated and enhanced by the baking process. It usually; occurs either during thebaking operation or shortly thereafter. The blackening effect has not only been found to exist between vinyl halides but also with compounds of the metals. Since pigments containing zinc and iron compounds especially are often quite cheap and otherwise'de sirable, this has been a definite disadvantage in the use of vinyl halide resins.

Some attempt has been made to remedy the blackening effect by adding pigments which appear to have a stabilizing action and hinder it. Pigments suchas, for example, blue lead, litharge and lead chromate appear toreduce the tendency toward blackening, but the effectiveness of these pigments appears to depend to a large extent upon the amount introduced, most eirective stabilization requiring the introduction of large invention an amount the present light or pastel shades as they mask any light colored pigments use It is an object of the present invention to produce a vinyl halide resin coating composition which shows considerable improvement over the disadvantages of prior art coating compositions. enumerated above. 1

It is also an object of this invention to provide a stable vinyl resin composition on zinc, iron or tin containing surfaces or including zinc or iron pigments.

I have found that ordinary vinyl halide resin compositions as previously used may be made compatible with zinc, iron and the like, and compounds thereof, by mixing acid having in addition to one'carboxyl group at least one other of a carboxyl or a hydroxyl group. All these acids may be employed but the group of hydroxy polycarboxylic acids is somewhat to be preferred. Organic acids of either aliphatic or aromatic types may be employed. As purely exemplary of these acids, a number which have been foundentirely satisfactory are malic, hydroxybutyric, oxalic, citric, lactic, tartaric, sue-- clnic, salicylic and maleic.

The amount of carboxylic acid which it is necessary to add to the vinyl halide resin varies depending upon-the type of composition and the acid employed. In accordance with the present of acid is employed sufllcient to resist substantially blackening of the, composition when it is baked on an iron, zinc or tin surface. Generally speaking, for normal baking conditions which usually range from about 20 minutes at 300 F. to about 20 minutes at 375 F. depending upon the type and thickness of material and the type of oven involved, 0.5% or in some cases even less than 0.1% of acid is sumcie'nt to provide a suitable coating. If more severe baking conditions of temperature and/or time are employed, more acid should be incorporated to obtain the best composition.

. A number of types of vinyl halide resin may be used in the present'invention, and resins which contain vinyl halide resins mixed with other resins such as, for example, methacrylate resins or vinyl esters, are very suitable for use in, this invention. One mixed vinyl resin which has been found very suitable for coating compositions of invention is formed by polymeriza tion of a mixture of vinyl halide and a vinyl ester hed coating compositions, but the introducwith them a carboxylic known and may be position.

ano e-:7

3 in varying proportions. For example, one may take 80 parts by weight of vinyl chloride, 20 parts by weight'of vinyl acetate in the presence of one part of benzoylperoxide in a suitable amount of toluol as a solvent. This mixture is heated to a temperature of 40 to 60' C. in an autoclave for about 24 hours. A reaction takes place and the resin terms. A number of vinyl halide type resins have been developed in the art. All are well The resins may be tomary manners when producing a coating com- The method of obtaining the mixture ofvinyl halide resin and acid is not in general important. Any convenient technique may be employed. For example, one may add powdered dry acid to powdered dry resin, or one may add a solution of acid to dry resin or one may add dry acid to a solution of resin, or again a solution of acid and a solution of resin may be mixed. Also, the acid may be added to the resin with lacquer-forming ingredients. It is desirable that relatively unitorm'distribution of the acid throughout the resin be employed.

Compositions of the present invention may have added to them any desired pigments, including not only iron and zinc pigments such as iron oxides, zinc oxides and mixed pigments contain- 1 ing iron and zinc compounds. but also pigments of various other characters, as, for example, titanium, lead or the like, pigments. Nor is t necessary that compositions of the present invention be coated only on base materials containing zinc or iron or' tin. They may be used to advantage on base materials of other metals, as. for example, aluminum, copper, brass and various alloys of these and other metals. Or, again, they may be used for coating upon non-metallic surfaces, as. for example, glass, porcelain. molded resins and the like.

The following examples show a few embodiments of the invention.

Example 1 There was provided a' solution including 12 grams of vinyl halide containing resin dissolved in 60cc. of butyl acetate. To that solution was added 100 cc. of a mixture of toluol and benzol. There was also provided a solution containing 3 grams of citric acid dissolved in 100 cc. of ethyl alcohol. The two solutions were mixed and the composition coated on a black iron sheet. The solvent was evaporated and the coated iron baked at a temperature of 320 F. for about eleven minutes. This treatment hardened the vinyl resin and made the same resistant as noted above. A second experiment was conductedusing the vinyl halide resin solution described above but without the addition of the citric acid solution. The treatment of the black iron sheet with this viny halide composition was identical and simultaneous with the aforesaid baking operation was completed the unmodified vinyl resin coating had turned a dark gray, verging on black. This was sharply contrasted with no discoloration or decomposition at all in the modified vinyl halide resin composition which remained clear and colorless after the baking was completed.

' Example 2 A composition of vinyl halide containing resin dissolved in 60 cc. of methyl butyl ketone and having added thereto 50 cc. of a toluol diluent. 2 grams of tartaric acid used in the present invention.

dissolved in solventsin cuswas prepared including 16 grams of tartaric acid in ethyl alcohol with continuous "stirring, the addition being iron sheet. After the Example 3 A solution was made with 18 grams of vinyl halide containing resin, 50 cc. of acetone and 15 cc. of toluol. 4 grams of lactic acid in the solid state were mixed with the solution and the two were ground together until the lactic acid was uniformly disseminated throughout the composition. A tinned iron plate was then brushed with the composition until the surface was uniformly coated. The solvent was removed and the article was baked at 345 F. for about eight minutes. The final baked product was clear and colorless and was perfectly satisfactory.

Example 4 A composition was made similar to that described in Example 1, cont ining citric acid, and.

into the composition was incorporated 5 grams of zinc chromate. The incorporation of said pigment was in accordance with the usual practice in a suitable mill. The composition was brushedon to a black iron sheet which was then baked at 325 F. for about ten minutes.

of the treatment there was no evidence of any change in the color of the composition, and preservation of the vinyl resin was accomplished.

Example 5 vinyl acetate in equal pro- This product was employed in a powdered state of fineness or 10 to 20 mesh.

It had asoftening point of about 128 C. To the powdered resin was added 15 cc. of a 5% solution a period of 5 to 10 minutes. The mixed composition was then evaporated at a low temperature in order to remove the alcohol from the mass. If agglomeration of the particles takes place during this operation it is advisable to subject the powdered material to a short grinding operation. The

composition so formed was completely stable and even upon standing for a relatively. long period of time no deterioration or appreciable change in the character of the resin takes place. When it is desired to use this composition it should be dissolved in the usual solvents in suitable amount with or without the addition of any other desired ingredients such as pigments, plasticizers, modifying agents. Such a solution was sprayed on the zinc article and baked for fifteen minutes at a temperature of 330F. This time of treatment was about twice that normally used in the baking or resins of this type. However, at the end of the operationlthe resin was clear and showed not the slightest evidence of discoloration or other signs of deterioration. In further tests the article so treated was baked at 355 F. for ten minutes at the end of which time the article was still in perfect condition.

For comparative purposes, the resin set forth above but not treated with any acid was made- At the termination mixed condensation product made gradually over 5 and the same proportions as the treated resin and a coating was made on a zinc article. The coating was baked for at 330 F. At the end of thisshort period oi! time breakdown of theresin h'ad definitely taken place and the discoloration was-quite pronounced. For all practical purposes the coated article was useless.

Example 6 20 grams of the condensation productofvlnyl chloride in the powdered state. and of a. fineness of about 20 mesh was mixed with 1 gram of powdered citric acid. The two powders were stirred in a suitable mixing device until the acid was uniformly composition was dissolved in suitable solvents to form a coating composition which was then sprayed upon an iron surface. The solvents were evaporated. The article was baked -at a temperature of 365 F. for seven minutes. The treatment caused the resin to become permanently hard. adherent and tough. There was no deterioration or discoloration of the surface,

Example 7 In order to determine the amount of stabilization eiiected with small quantities of organic carboxylic acid under relatively severe baking conditions, three diflerent acids were incorporated with a vinyl halide resin base lacquer in varying amounts. The diflerent lacquers were poured on to iron plates and baked for thirty minutes at 350 F. The results obtained are tabulated below. 'In the table, 13 indicates a pour which turned black; SLB indicates one in which there was substantially less blackening oi the coating; and indicates one which remained clear.

used with excellent results.

In some or these cases large excesses or acid produced some yellowing or the coating.

The exact order of procedure and the proportions ,or the ingredients may be varied at will, as a wide range 01' variation of such iactors may be What is claimed is:

A coating composition which comprises a vinyl halide resin and a solvent and having incorporated therewith a acid in quantity suflicient to resist'substantially a period of three minutesdisseminated throughout the resin. The

blackening oi the coating when the composition is baked one. surface selected from theclass consisting of iron, zinc, and tin surfaces.

'2. A metalsuriace selected from the class consisting ,ofiron, zi nc, and tin suriaces having baked thereona coating which comprises a vinyl pound pigments, having incorporated therewith 8. A composition a. hydroxy polycarboxylic acid in quantity suiiicient to resist substantially blackening of the coating composition on'baking.

4. A composition 01' matter suitable for preparinga coating composition which comprises a vinyl halide resinhaving incorporated therewitha hydroxy polycarboxylic acid in quantity sumcient to resist substantially blackening or the coating when the composition is baked in contact with a surface selected from the class consisting of iron, zinc, and tin surfaces..

5. A coating composition according to claim 1 in which the carboxylicacid is citric acid. a 6. A coating composition according to claim 1 in which the carboxylic acid is tartaric acid.

7. A coating composition according to claim 1 in which the carboxylic acid is'malic'acid.

oi matter according to claim 4 in which the carboxylic acid is citric acid,

9.. A composition or matter according to. claim 4 in which the carboxylic acid is tartaric acid.

- 10. A composition of matter according to claim 4 in which the carboxylic acid is malic acid.

11. A metal surface according to claim 2 in which the carboxylic acid is citric acid;

12. A metal surface according to claim 2 in which the carboxylic acid is tartaric acid.

13. A metal surface according to claim 2 in which the carboxylic acid is malic acid.

7 CARL L. SHAPIRO.

- file of this patent:

hydroxy polycarboxylic Number UNITED STATES [PATENTS Number Name. 1 Date 2,137,627 Reed ov. 22, 1938 FOREIGN PATENTS Country Date 454.232 Great Britain Sept. 25. 1936 

